Liquid Crystal Dispensing System And Method Of Dispensing Liquid Crystal Material Using Same

ABSTRACT

A liquid crystal dispensing system includes a container to contain liquid crystal to be dispensed, a discharge pump to receive the liquid crystal from the container and to discharge the liquid crystal, a nozzle to dispense the liquid crystal discharged from the discharge pump onto a substrate, and a control unit to control a dispensing amount of liquid crystal discharged from the discharge pump and to compensate the dispensing amount when the dispensing amount of liquid crystal exceeds a limitation value.

The present application claims the benefit of Korean Patent ApplicationNo. 2003-29456 filed in Korea on May 9, 2003. The present applicationfurther incorporates by reference U.S. patent application Ser. No.10/421,714, which has published as US Patent Publication No.2004-0011422-A1.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal dispensing system, andmore particularly, to a liquid crystal dispensing system capable ofpreventing an inferiority of a liquid crystal display device bydispensing a precise amount of liquid crystal onto a substrate and amethod of dispensing liquid crystal using the same.

2. Description of the Related Art

Recently, various portable electric devices, such as mobile phones,personal digital assistant (PDA), and note book computers, have beendeveloped because of their small size, light weight, and power-efficientoperations. Accordingly, flat panel display devices, such as liquidcrystal displays (LCDs), plasma display panels (PDPs), field emissiondisplays (FEDs), and vacuum fluorescent displays (VFDs), have beendeveloped. Of these flat panel display devices, the LCDs are currentlymass produced because of their simple driving scheme and superior imagequality.

FIG. 1 is a cross sectional view of an LCD device according to therelated art. In FIG. 1, an LCD device 1 comprises a lower substrate 5,an upper substrate 3, and a liquid crystal layer 7 formed therebetween.The lower substrate 5 is a driving device array substrate, and includesa plurality of pixels (not shown) and a driving device, such as a thinfilm transistor (TFT), formed on each pixel. The upper substrate 3 is acolor filter substrate, and includes a color filter layer forreproducing real color. In addition, a pixel electrode and a commonelectrode are formed on the lower substrate 5 and the upper substrate 3,respectively. An alignment layer is formed on both the lower and uppersubstrates 5 and 3 to align liquid crystal molecules of the liquidcrystal layer 7. The lower substrate 5 and the upper substrate 3 areattached along a perimeter by a sealant 9, and the liquid crystal 7 isconfined within the perimeter. In operation, the liquid crystalmolecules of the liquid crystal layer 7 are reoriented by the drivingdevice formed on the lower substrate 5 to control amounts of lighttransmitted through the liquid crystal layer 7, thereby displaying animage.

FIG. 2 is a flow chart of a fabrication method for an LCD deviceaccording to the related art. In FIG. 2, a fabrication method includesthree sub-processes for manufacturing an LCD device: a driving devicearray substrate process for forming the driving device on the lowersubstrate 5; a color filter substrate process for forming the colorfilter on the upper substrate 3; and a cell process.

In Step S101, a plurality of gate lines and data lines are formed on thelower substrate 5 to define a pixel area by the driving device arrayprocess, and the thin film transistor connected to both the gate lineand the data line is formed on the each pixel area. In addition, a pixelelectrode, which is to be connected to the thin film transistor to drivethe liquid crystal layer according to a signal applied through the thinfilm transistor, is formed by the driving device array process. In StepS104, R, G, and B color filter layers for reproducing the color and acommon electrode are formed on the upper substrate 3 by the color filterprocess.

In Steps S102 and S105, alignment layers are formed on the lowersubstrate 5 and the upper substrate 3. Then, the alignment layers areindividually rubbed to induce surface anchoring (i.e. a pretilt angleand alignment direction) for the liquid crystal molecules of the liquidcrystal layer 7. In Step S103, a spacer is dispersed onto the lowersubstrate 5 for maintaining a uniform cell gap between the lower andupper substrates 5 and 3. In Step S106, a sealant is printed along outerportions of the upper substrate 3.

In Step S107, the lower and upper substrates 5 and 3 are assembledtogether by compression. The lower substrate 5 and the upper substrate 3are both made of glass substrates, and include a plurality of unit panelareas on which the driving device and the color filter layer are formed.In Step S108, the assembled upper and lower glass substrates 5 and 3 arecut into unit panels. In Step S109, liquid crystal material is injectedinto the gap formed between the upper and lower substrates 5 and 3 ofthe unit panels through a liquid crystal injection hole. The filled unitpanel is completed by encapsulating the liquid crystal injection hole.In Step S110, the filled and sealed unit panel is tested.

FIG. 3 is a schematic view of a liquid crystal injection system forfabricating an LCD device according to the related art. In FIG. 3, acontainer 12 in which liquid crystal material 14 is contained is placedin a vacuum chamber 10, and the liquid crystal display panel 1 islocated at an upper side of the container 12. Then, the vacuum chamber10 is connected to a vacuum pump (not shown) to maintain a predeterminedvacuum/pressure state within the vacuum chamber 10. In addition, aliquid crystal display panel moving device (not shown) is installed inthe vacuum chamber 10 to move the liquid crystal display panel 1 fromthe upper side of the container 12 to a surface of the liquid crystalmaterial 14, thereby contacting an injection hole 16 of the liquidcrystal display panel 1 to the liquid crystal material 14. Accordingly,this method is commonly called as a liquid crystal dipping injectionmethod.

When the vacuum/pressure level within the chamber 10 is decreased by aninflow of nitrogen gas (N₂) into the vacuum chamber 10 in the state thatthe injection hole 16 of the liquid crystal display panel 1 contacts thesurface of the liquid crystal material 14, the liquid crystal material14 is injected into the liquid crystal display panel 1 through theinjection hole 16 by the pressure differential between thevacuum/pressure level within the liquid crystal display panel 1 and thepressure/level within the vacuum chamber 10. After the liquid crystalmaterial 14 is completely filled into the liquid crystal display panel1, the injection hole 16 is sealed by a sealant to seal the liquidcrystal material 14 within the liquid crystal display panel 1.Accordingly, this method is called as a vacuum injection method.

However, there are several problems with both the liquid crystal dippinginjection method and/or vacuum injection method. First, an overall timefor injection of the liquid crystal material 14 into the panel 1 isrelatively long for either method. In general, a gap thickness betweenthe driving device array substrate and the color filter substrate in theliquid crystal display panel 1 is relatively narrow, i.e., a fewmicrometers. Accordingly, a relatively small amount of liquid crystalmaterial 14 is injected into the liquid crystal display panel 1 per unittime. For example, it takes about 8 hours to completely inject theliquid crystal material 14 into a 15-inch liquid crystal display panel,and thus, fabricating efficiency is decreased. Second, consumption ofthe liquid crystal material 14 during the liquid crystal injectionmethod is large. Only a small amount of the liquid crystal material 14in the container 12 is actually injected into the liquid crystal displaypanel 1. Accordingly, during loading of the liquid crystal display panel1 into the vacuum chamber 10, the unused liquid crystal material 14 isexposed to atmosphere or to certain gases, thereby contaminating theliquid crystal material 14. Thus, any remaining liquid crystal material14 must be discarded after the injection of the liquid crystal material14 into a plurality of liquid crystal display panels 1, therebyincreasing fabricating costs.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a liquid crystaldispensing system and method of dispensing liquid crystal material usingthe same that substantially obviates one or more of the problems due tolimitations and disadvantages of the related art.

An object of the present invention is to provide a liquid crystaldispensing system for directly dispensing liquid crystal onto a glasssubstrate of a large area including at least one liquid crystal paneland a method of dispensing liquid crystal using the same.

Another object of the present invention is to provide a liquid crystaldispensing system capable of preventing an inferiority of a liquidcrystal display device by dispensing a precise amount of liquid crystalonto a substrate and a method of dispensing liquid crystal using thesame.

Another object of the present invention is to provide a liquid crystaldispensing system capable of quickly compensating a dispensing amount ofliquid crystal and preventing an inferiority of a substrate and a methodof dispensing liquid crystal using the same.

Additional features and advantages of the invention will be set forth inthe description which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention. Theobjectives and other advantages of the invention will be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described herein, aliquid crystal dispensing system, comprises a container to containliquid crystal to be dispensed; a discharge pump to receive the liquidcrystal from the container and to discharge the liquid crystal; a nozzleto dispense the liquid crystal discharged from the discharge pump onto asubstrate; and a control unit to control a dispensing amount of liquidcrystal discharged from the discharge pump and to compensate thedispensing amount when the dispensing amount of liquid crystal exceeds alimitation value.

In another aspect, a liquid crystal dispensing system, comprises aplurality of dispensers to dispense liquid crystal onto a substratedefining a plurality of unit panels; and a control unit to control adispensing amount of liquid crystal dispensed from the liquid crystaldispenser and to compensate the dispensing amount when the dispensingamount of liquid crystal exceeds a limitation value.

In another aspect, a liquid crystal dispensing method, comprises thesteps of calculating a dispensing amount and a dispensing position ofliquid crystal and setting a liquid crystal dispensing system; driving asubstrate and to position a liquid crystal dispensing system at thedispensing position; controlling a fixation angle of a discharge pump bydriving a second motor in accordance with the calculated dispensingamount; operating the discharge pump by driving a first motor todispense liquid crystal onto the substrate; measuring a dispensingamount of liquid crystal dispensed onto the substrate; calculating adifferential value between the measured dispensing amount and the presetdispensing amount; and controlling a dispensing of liquid crystal bycomparing the differential value with a limitation value.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention. In the drawings:

FIG. 1 is a cross sectional view of a liquid crystal display (LCD)device according to the related art;

FIG. 2 is a flow chart of a fabrication method for an LCD deviceaccording to the related art;

FIG. 3 is a schematic view of a liquid crystal injection system forfabricating an LCD device according to the related art;

FIG. 4 is a cross sectional view of an LCD device fabricated by a liquidcrystal dispensing method according to an embodiment of the presentinvention;

FIG. 5 is a flow chart of a fabrication method of an LCD device by aliquid crystal dispensing method according to an embodiment of thepresent invention;

FIG. 6 is a view of a basic concept of a liquid crystal dispensingmethod;

FIG. 7 is a perspective view of a liquid crystal dispenser according toan embodiment of the present invention;

FIG. 8 is a disassembled perspective view of the liquid crystaldispenser according to an embodiment of the present invention;

FIG. 9A is a perspective view of a liquid crystal discharge pump of theliquid crystal dispenser according to an embodiment of the presentinvention;

FIG. 9B is a disassembled perspective view of the liquid crystaldischarge pump;

FIG. 10 is a view showing a state that the liquid crystal discharge pumpis fixed to a fixing unit;

FIGS. 11A to 11D are operational views of the liquid crystal dischargepump;

FIG. 12 is a view of the liquid crystal discharge pump of which afixation angle has been increased;

FIG. 13 is a block diagram of a control unit of a liquid crystaldispensing system according to an embodiment of the present invention;

FIG. 14 is a block diagram of a dispensing amount setting unit;

FIG. 15 is a block diagram of a dispensing amount compensating unit;

FIG. 16 is a block diagram of a motor driving unit;

FIG. 17 is a flow chart of a liquid crystal dispensing method onto asubstrate using the liquid crystal dispensing system;

FIG. 18 is a flow chart of a dispensing amount error compensating methodof liquid crystal in case that an error of a dispensing amount isgenerated;

FIG. 19 is a view illustrating one example of dispensing liquid crystalby a plurality of liquid crystal dispensers onto a substrate where aplurality of liquid crystal panels are formed; and

FIG. 20 is a view illustrating another example of dispensing liquidcrystal by a plurality of liquid crystal dispensers onto a substratewhere a plurality of liquid crystal panels are formed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings.

In order to solve the problems of the related liquid crystal injectionmethods such as a liquid crystal dipping method or a liquid crystalvacuum injection method, a liquid crystal dropping method has beenrecently introduced. The liquid crystal dropping method is a method forforming a liquid crystal layer by directly dropping the liquid crystalonto the substrates and spreading the dropped liquid crystal over theentire panel by pressing together the substrates during the assemblingprocedure of the substrates rather than by injecting the liquid crystalinto the empty unit panel by the pressure difference between the innerand outer sides of the panel. According to the above liquid crystaldropping method, the liquid crystal is directly dropped onto thesubstrate in a short time period so that the liquid crystal layer in aLCD of larger area can be formed quickly. In addition, the liquidcrystal consumption can be minimized due to the direct dropping of theliquid crystal as much as required amount, and therefore, thefabrication cost can be reduced.

FIG. 4 is a view illustrating a basic concept of a liquid crystaldispensing method according to an embodiment of the present invention.In FIG. 4, liquid crystal material 107 may be dropped onto a lowersubstrate 105 having a driving device prior to assembling the lowersubstrate 105 and an upper substrate 103 having a color filter.Alternatively, the liquid crystal material 107 may be dropped onto theupper substrate 103 upon which the color filter is formed. For example,the liquid crystal material 107 may be formed either on a thin filmtransistor (TFT) substrate or on a color filter (CF) substrate.

A sealant 109 may be applied along at least an outer perimeter portionof the upper-substrate 103. Then, the upper substrate 103 and the lowersubstrate 105 may be assembled together by pressing the upper and lowersubstrates 103 and 105 together to form an LCD display panel 101.Accordingly, the drops of the liquid crystal material 107 spread outbetween the upper and lower substrates 103 and 105 by pressure appliedto the upper and/or lower substrates 103 and 105, thereby forming aliquid crystal material layer of uniform thickness between the uppersubstrate 103 and the lower substrate 105. Thus, in the exemplary LCDdevice fabrication method, the liquid crystal material 107 may bedropped onto the lower substrate 105 before the upper and lowersubstrates 103 and 105 are assembled together to form the LCD displaypanel 101.

FIG. 5 is a flow chart of an exemplary LCD device fabrication methodaccording to an embodiment of the present invention. In Step S201, adriving device, such as a TFT, is formed on an upper substrate using aTFT array process. In Step S204, a color filter layer is formed on alower substrate 105 using a color filter process. The TFT array processand the color filter process, which are generally similar to those ofcommon processes, may be preferably applied to glass substrates having aplurality of unit panel areas. Herein, the upper and lower substratesmay include a glass substrate having an area about 1000×1200 mm² ormore. However, glass substrates having smaller areas also may be used.

In Steps S202 and S205, alignment layers may be formed and rubbed onboth the upper and lower substrates. In Step S203, liquid crystalmaterial may be dropped onto a liquid crystal display unit panel area ofthe lower substrate 105. In Step S206, sealant is applied along at leastan outer perimeter portion area of the liquid crystal display unit panelarea on the upper substrate.

In Step S207, the upper and lower substrates are disposed to face eachother, and compressed to join the upper and lower substrates with eachother using the sealant. Accordingly, the dropped liquid crystalmaterial evenly spreads out between the upper and lower substrates andthe sealant. In Step S208, the assembled upper and lower substrates areprocessed and cut into a plurality of liquid crystal display unitpanels. In Step S209, the liquid crystal display unit panels are tested.

The LCD device fabrication method using the liquid crystal droppingmethod of FIG. 5 is different from the LCD device fabrication methodusing the related art liquid crystal injection method in that a vacuuminjection of liquid crystal is not used but rather a liquid crystaldropping, thereby reducing the processing time of a large area glasssubstrate. That is, in the LCD device fabrication method using theliquid crystal injection method of FIG. 2, liquid crystal is injectedthrough an injection hole and then the injection hole is encapsulated byan encapsulation material. However, in the LCD device fabrication methodusing the liquid crystal dropping method, liquid crystal is directlydropped onto the substrate and does not require the process sealing ofthe injection hole. Although not shown in FIG. 2, in the LCD devicefabrication method using the liquid crystal injection method, thesubstrate is contacting the liquid crystal at the time of injectingliquid crystal so that an outer surface of the panel is contaminated bythe liquid crystal. Therefore, a process for washing the contaminatedsubstrate is required. However, in the LCD device fabrication methodusing the liquid crystal dropping method, liquid crystal is directlydropped onto the substrate so that the panel is not contaminated by theliquid crystal, and a washing process is not required. The LCD devicefabrication method using the liquid crystal dropping method is moresimple than the LCD device fabrication method using the liquid crystalinjection method, thereby having an increased fabricating efficiency andan increased yield.

In the LCD device fabrication method using the liquid crystal droppingmethod, a dropping position of liquid crystal and a dropping amount ofliquid crystal have the most influence on forming a liquid crystal layerwith a desired thickness. Especially, since the thickness of a liquidcrystal layer is closely related to a cell gap of a liquid crystalpanel, a precise dropping position of liquid crystal and a preciseamount of liquid crystal are very important to prevent inferiority of aliquid crystal panel. To drop a precise amount of liquid crystal onto aprecise position, a liquid crystal dispenser is provided in the presentinvention.

FIG. 6 is a perspective view of another exemplary LCD device fabricationmethod according to an embodiment of the present invention. In FIG. 6,liquid crystal material 107 is dispensed onto a glass substrate 105using a liquid crystal dispenser 120 positioned above the glasssubstrate 105. Although not shown, the liquid crystal material 107 maybe contained in the liquid crystal dispenser 120. As the liquid crystalmaterial 107 is dropped onto the glass substrate 105, the glasssubstrate 105 is moved along x- and y-directions at a predeterminedspeed, while the liquid crystal dispenser 120 discharges the liquidcrystal material 107 at predetermined time intervals. Accordingly, theliquid crystal material 107 dropping onto the glass substrate 105 may bearranged along x- and y-directions with predetermined intervalstherebetween. Alternatively, the glass substrate 105 may be fixed whilethe liquid crystal dispenser 120 moves along the x- and y-directions todrop the liquid crystal material 107 at predetermined intervals.However, a shape of the liquid crystal material 107 may be altered byany vibration of the liquid crystal dispenser 120, whereby errors in thedropping position and the dropping amount of the liquid crystal material107 may occur. Therefore, it may be preferable that the liquid crystaldispenser 120 be fixed and that the glass substrate 105 be moved.

FIG. 7 is a perspective view of the liquid crystal dispenser accordingto an embodiment of the present invention, and FIG. 8 is a disassembledperspective view of the liquid crystal dispenser according to anembodiment of the present invention. In FIGS. 7A and 7B, the liquidcrystal dispenser 120 may include a cylindrically shaped liquid crystalmaterial container 122 accommodated in a case 123. The liquid crystalmaterial container 122 is formed of polyethylene, and the liquid crystal107 is contained in the liquid crystal material container 122. The case123 is formed of a stainless steel and accommodates the liquid crystalmaterial container 122 therein. Since the polyethylene has a highplasticity, a container of a desired shape can be easily formed with thepolyethylene. Also, the polyethylene is non-reactive with the liquidcrystal material 107 when the liquid crystal material 107 is containedtherein, thereby being mainly used as the liquid crystal materialcontainer 122. However, the polyethylene has a low strength and maytherefore become easily deformed by application of stress. When theliquid crystal material container 122 is deformed, the liquid crystalmaterial 107 may not be precisely dispensed onto a substrate.Accordingly, the liquid crystal material container 122 may be insertedwithin the case 123 formed of stainless steel having a high strength.

Although not shown, a gas supply tube may be arranged at an upperportion of the liquid crystal material container 122 so that inert gas,such as nitrogen, may be provided thereto. The gas is supplied withinportions of the liquid crystal material container 122 not occupied bythe liquid crystal material 107. Accordingly, the gas presses on theliquid crystal material 107 and induces the liquid crystal material tobe dispensed onto the substrate.

The liquid crystal material container 122 may include a material thatdoes not deform, such as stainless steel. Accordingly, when the liquidcrystal material container 122 is formed out of stainless steel, thecase 123 may not be required, thereby reducing fabrication costs of theliquid crystal dispenser 120. The interior of the liquid crystalmaterial container 122 may be coated with a fluorine resin, therebypreventing the liquid crystal material 107 contained within the liquidcrystal material container 122 from chemically reacting with sidewallsof the liquid crystal material container 122.

A liquid crystal discharge pump 140 is arranged at a lower portion ofthe liquid crystal material container 122. The liquid crystal dischargepump 140 is for discharging a certain amount of liquid crystal from theliquid crystal material container 122 to be dropped onto a substrate.The liquid crystal discharge pump 140 is provided with a liquid crystalsuction opening 147 connected to the liquid crystal material container122 for drawing in liquid crystal in accordance with the operation ofthe liquid crystal discharge pump 140, and a liquid crystal dischargeopening 148 at the opposite side of the liquid crystal suction opening147 for discharging liquid crystal in accordance with the operation ofthe liquid crystal discharge pump 140.

In FIG. 8, a first connecting tube 126 is coupled to the liquid crystalsuction opening 147. Although the liquid crystal suction opening 147 iscoupled to the first connecting tube 126 by being inserted in drawing,the liquid crystal suction opening 147 can be coupled to the firstconnecting tube 126 by a coupling member such as a screw. A pin 128 suchas an injection needle of which inside is penetrated is formed at oneside of the first connecting tube 126. A pad (not shown) formed of amaterial having a high contraction characteristic and a hermeticcharacteristic such as silicon or butyl rubber group is arranged at alower portion of the liquid crystal material container 122 fordischarging liquid crystal to the first connecting tube 126. The pin 128is inserted into the liquid crystal material container 122 through thepad, thereby introducing the liquid crystal 107 of the liquid crystalmaterial container 122 into the liquid crystal suction opening 147. Whenthe pin 128 is inserted into the liquid crystal material container 122,the pad forms a seal around the pin 128, thereby preventing leakage ofthe liquid crystal 107 to the insertion region of the pin 128. Since theliquid crystal suction opening 147 and the liquid crystal materialcontainer 122 are coupled to each other by the pin and the pad, thecoupling structure is simple and the coupling/detachment is facilitated.Alternatively, the liquid crystal suction opening 147 and the firstconnecting tube 126 may be formed as a unit. In this case, the pin 128is formed at the liquid crystal suction opening 147 and is directlyinserted into the liquid crystal material container 122 to dischargeliquid crystal, thereby having a simple structure.

A nozzle 150 is formed at a lower portion of the liquid crystaldischarge pump 140. The nozzle 150 is connected to the liquid crystaldischarge opening 148 of the liquid crystal discharge pump 140 through asecond connecting tube 160, thereby dropping the liquid crystal 107discharged from the liquid crystal discharge pump 140 onto thesubstrate. The second connecting tube 160 may be formed of an opaquematerial. However, the second connecting tube 160 is formed of atransparent material due to the following reasons.

At the time of the liquid crystal dropping, vapor is contained in theliquid crystal 107 and a dispensing amount of the liquid crystal 107dispensed onto the substrate can not be precisely controlled. Therefore,the vapor has to be removed at the time of the liquid crystal dropping.The vapor is already contained in the liquid crystal 107 to be containedin the liquid crystal material container 122. Even if the vaporcontained in the liquid crystal 107 can be removed by a vapor removingdevice, the vapor is not completely removed. Also, vapor may begenerated when the liquid crystal 107 is introduced into the liquidcrystal discharge pump 140 from the liquid crystal material container122. Accordingly, it is impossible to completely remove the vaporcontained in the liquid crystal 107. Therefore, it is the best method toremove vapor by stopping the operation of the liquid crystal dispenserat the time of the vapor occurrence. The reason why the secondconnecting tube 160 is formed of a transparent material is to preventinferiority of the LCD device by easily finding vapor contained in theliquid crystal material container 122 or vapor generated from the liquidcrystal material container 122. The vapor can be found by the user'snaked eyes, and can be automatically detected by a first sensor 162 suchas a photo coupler installed at both sides of the second connecting tube160, in which the latter case can prevent the inferiority of the LCDdevice more certainly.

The nozzle 150 into which the discharged liquid crystal is introducedthrough the second connecting tube 160 is provided with a protectionunit 152 for protecting the nozzle 150 from external stress and etc. atboth side surfaces thereof. Also, a second sensor 154 for detectingwhether vapor is contained in the liquid crystal dropped from the nozzle150 or whether liquid crystal masses on the surface of the nozzle 150 isinstalled at the protection unit 154 at the lower portion of the nozzle150.

The phenomenon that the liquid crystal masses on the surface of thenozzle 150 prevents a precise dropping of the liquid crystal 107. Whenthe liquid crystal drops through the nozzle 150, a certain amount ofliquid crystal spreads on the surface of the nozzle 150 even if a presetamount of liquid crystal is discharged from the liquid crystal dischargepump 140. According to this, liquid crystal of less amount than thepreset amount is dispensed onto the substrate. Also, when the liquidcrystal that masses on the surface of the nozzle 150 drops on thesubstrate, inferiority of the LCD device may be generated. To preventthe liquid crystal from massing on the surface of the nozzle 150,material such as fluorine resin having a high contact angle with liquidcrystal, that is a hydrophobic material, may be deposited on the surfaceof the nozzle 150 by a dipping method or a spray method. By thedeposition of the fluorine resin, the liquid crystal does not spread onthe surface of the nozzle 150, but is dispensed onto the substratethrough the nozzle 150 as a perfect drop shape.

The liquid crystal discharge pump 140 is in a state of being insertedinto a rotating member 157, and the rotating member 157 is fixed to afixing unit 155. The rotating member 157 is connected to a first motor131. As the first motor 131 is operated, the rotating member 157 isrotated and the liquid crystal discharge pump 140 fixed to the rotatingmember 157 is operated.

The liquid crystal discharge pump 140 is in contact with one side of aliquid crystal capacity amount controlling member 134 having a barshape. A hole is formed at another side of the liquid crystal capacityamount controlling member 134, and a rotational shaft 136 is insertedinto the hole. A screw is formed at the perimeter of the hole of theliquid crystal capacity amount controlling member 134 and the rotationalshaft 136, so that the liquid crystal capacity amount controlling member134 and the rotational shaft 136 are screw-coupled to each other. Oneend of the rotational shaft 136 is connected to a second motor 133, andanother end thereof is connected to a controlling lever 137.

The discharge amount of liquid crystal from the liquid crystal materialcontainer 122 through the liquid crystal discharge pump 140 is variedaccording to a fixation angle of the liquid crystal discharge pump 140to the rotating member 157. That is, a liquid crystal capacity amount ofthe liquid crystal discharge pump 140 is varied according to an anglethat the liquid crystal discharge pump 140 is fixed to the rotatingmember 157. When the second motor 133 connected to the rotational shaft136 is driven (automatically controlled) or the controlling lever 137 isoperated (manually controlled), the rotational shaft 136 is rotated.According to this, one end of the liquid crystal capacity amountcontrolling member 134 screw-coupled to the rotational shaft 136 movesback and forth (linear direction) along the rotational shaft 136.Accordingly, as one end of the liquid crystal capacity amountcontrolling member 134 moves, a force applied to the liquid crystaldischarge pump 140 is varied, and therefore, the fixation angle of theliquid crystal discharge pump 140 is varied.

As aforementioned, the first motor 131 operates the liquid crystaldischarge pump 140 to discharge liquid crystal of the liquid crystalmaterial container 122 and to drop the liquid crystal onto thesubstrate. Also, the second motor 133 controls the fixation angle of theliquid crystal discharge pump 140 fixed to the rotating member 157 tocontrol the amount of liquid crystal discharged from the liquid crystaldischarge pump 140.

A single dispensing amount of liquid crystal dropped onto the substratethrough the liquid crystal discharge pump 140 is very minute, andtherefore, a variation amount of the liquid crystal discharge pump 140controlled by the second motor 133 is also minute. Accordingly, tocontrol the discharge amount of the liquid crystal discharge pump 140,an inclination angle of the liquid crystal discharge pump 140 has to becontrolled very precisely. For the precise control, a step motoroperated by a pulse input value is used as the second motor 133.

FIG. 9A is a perspective view of the liquid crystal discharge pump, andFIG. 9B is a disassembled perspective view of the liquid crystaldischarge pump. In FIGS. 9A and 9B, the liquid crystal discharge pump140 includes: a case 141 having the liquid crystal suction opening 147and the liquid crystal discharge opening 148; a cap 144 having anopening at an upper portion thereof and coupled to the case 141; acylinder 142 inserted into the case 141 for drawing in liquid crystal; asealing member 143 for sealing the cylinder 142; an o-ring 144 apositioned above the cap 144 for preventing liquid crystal from beingleaked; and a piston 145 up-down moved and rotated by being insertedinto the cylinder 142 through the opening of the cap 144, for drawing inand discharging the liquid crystal 107 through the liquid crystalsuction opening 147 and the liquid crystal discharge opening 148. A head146 a fixed to the rotating member 157 is installed above the piston145, and a bar 146 b is installed at the head 146 a. The bar 146 b isinserted into a hole (not shown) of the rotating member 157 and isfixed, thereby rotating the piston 145 when the rotating member 157 isrotated by a force of the first motor 131.

In FIG. 9B, a groove 145 a is formed at the end of the piston 145. Thegroove 145 a has an area corresponding to approximately ¼ (or less thanthat) of a sectional area of a circle shape of the piston 145. Thegroove 145 a opens and closes the liquid crystal suction opening 147 andthe liquid crystal discharge opening 148 when the piston 145 is rotated(that is, up and down moved), thereby drawing in and discharging liquidcrystal through the liquid crystal suction opening 147 and the liquidcrystal discharge opening 148.

Operation of the liquid crystal discharge pump 140 will be explained asfollows.

FIG. 10 is a view showing a state that the liquid crystal discharge pump140 is fixed to the rotating member 157. In FIG. 10, the piston 145 isfixed to the rotating member 157 with a certain angle (α). The bar 146 bformed at the piston head 146 a is inserted into a hole 159 formedinside the rotating member 157, so that the piston 145 and the rotatingmember 157 are coupled to each other. Although not shown, a bearing isprovided inside the hole 159 and thereby the bar 146 b of the piston 145inserted into the hole 159 can move back and forth and right and left.When the first motor 131 is operated, the rotating member 157 is rotatedand thereby the piston 145 coupled to the rotating member 157 isrotated.

Herein, if the fixation angle (α) or the liquid crystal discharge pumpfor the rotating member 157, that is, the fixation angle (α) of thepiston 145 for the rotating member 157 is supposed to be 0, the piston145 performs only a rotational motion along the rotating member 157.However, since the fixation angle (α) of the piston 145 is not 0,substantially (that is, the piston 145 is fixed with a certain angle),the piston 145 not only rotates along the rotating member 157 but alsoup-down moves.

If the piston 145 moves upwardly by rotating with a certain angle, aspace is formed inside the cylinder 142 and liquid crystal is drawn intothe space through the liquid crystal suction opening 147. Then, if thepiston 145 moves downwardly by rotating more, the liquid crystal in thecylinder 142 is discharged through the liquid crystal discharge opening148. Herein, the groove 145 a formed at the piston 145 opens and closesthe liquid crystal suction opening 147 and the liquid crystal dischargeopening 148 at the time of sucking and discharging the liquid crystal bythe rotation of the piston 145.

Hereinafter, operation of the liquid crystal disc charge pump 140 willbe explained in more detail with reference to FIGS. 11A to 11D. In FIGS.11A to 11D, the liquid crystal discharge pump 140 discharges the liquidcrystal 107 of the liquid crystal material container 122 to the nozzle150 through 4 strokes. FIGS. 11A and 11C are cross strokes, FIG. 11B isa suction stroke through the liquid crystal suction opening 147, andFIG. 11D is a discharge stroke through the liquid crystal dischargeopening 148.

In FIG. 11A, the piston 145 fixed to the rotating member 157 with acertain angle (a) rotates accordingly as the rotating member 157rotates. At this time, the liquid crystal suction opening 147 and theliquid crystal discharge opening 148 are closed by the piston 145.

When the rotating member 157 rotates with approximately 45°, the piston145 rotates and the liquid crystal suction opening 147 is open by thegroove 145 a of the piston 145 as shown in FIG. 11B. The bar 146 b ofthe piston 145 is inserted into the hole 159 of the rotating member 157,thereby coupling the rotating member 157 and the piston 145.Accordingly, as the rotating member 157 rotates, the piston 145 rotates.At this time, the bar 146 b rotates along a rotating plane.

Since the piston 145 is fixed to the rotating member 157 with a certainangle and the bar 146 b rotates along the rotating plane, the piston 145moves upwardly accordingly as the rotating member 157 rotates. Also,accordingly as the rotating member 157 rotates, a space is formed at thecylinder 142 positioned at the lower portion of the piston 145 since thecylinder 142 is fixed. Therefore, liquid crystal is drawn into the spacethrough the liquid crystal suction opening 147 that has been open by thegroove 145 a. The suction stroke of liquid crystal continues until thesuction stroke of FIG. 11C starts (the liquid crystal suction opening147 is closed) as the rotating member 157 rotates with approximately 45°after the suction stroke starts (that is, the liquid crystal suctionopening 147 is open).

Then, as shown in FIG. 11D, the liquid crystal discharge opening 148 isopen and the piston 145 downwardly moves accordingly as the rotatingmember 157 rotates more, so that the liquid crystal sucked into thespace inside the cylinder 142 is discharged through the liquid crystaldischarge opening 148 (discharge stroke). As aforementioned, the liquidcrystal discharge pump 140 repeats four strokes that is, the first crossstroke, the suction stroke, the second cross stroke, and the dischargestroke, thereby discharging the liquid crystal 107 contained in theliquid crystal material container 122 to the nozzle 150. Herein, thedischarge amount of liquid crystal is varied according to an up-downmotion range of the piston 145. The up-down motion range of the piston145 is varied according to the angle of the liquid crystal dischargepump 140 fixed to the rotating member 157.

FIG. 12 is a view showing that the liquid crystal discharge pump isfixed to the rotating member with an angle of B. When compared to theliquid crystal discharge pump 140 of FIG. 10 fixed to the rotatingmember 157 with the angle of α, the liquid crystal discharge pump 140 ofFIG. 12 fixed to the rotating member 157 with an angle of β(>α) enablesthe piston 145 to upwardly move more highly. That is, the more the angleof the liquid crystal discharge pump 140 fixed to the rotating member157 is, the more the amount of the liquid crystal 107 drawn into thecylinder 142 at the time of the piston motion is. This means that thedischarge amount of liquid crystal can be controlled by adjusting theangle of the liquid crystal discharge pump 140 fixed to the rotatingmember 157.

The angle of the liquid crystal discharge pump 140 fixed to the rotatingmember 157 is controlled by the liquid crystal capacity amountcontrolling member 134 of FIG. 7, and the liquid crystal capacity amountcontrolling member 134 is moved by driving the second motor 133. Thatis, the angle of the liquid crystal discharge pump 140 fixed to therotating member 157 is controlled by controlling the second motor 133.

The fixation angle of the liquid crystal discharge pump 140 can bemanually adjusted by handling the angle controlling lever 137 by theuser. However, in this case, a precise adjustment is not possible, a lotof time is required, and the driving of the liquid crystal dischargepump has to be stopped during the operation. Therefore, it is preferableto adjust the fixation angle of the liquid crystal discharge pump 140 bythe second motor 133. The fixation angle of the liquid crystal dischargepump 140 is measured by a sensor 139 such as a linear variabledifferential transformer. If the fixation angle exceeds a preset angle,the sensor 139 rings the alarm thus to prevent the liquid crystaldischarge pump 140 from being damaged. Although not shown, the secondmotor 133 is connected to a control unit by wire or wirelessly. Eachkind of information such as a preset dispensing amount of liquid crystaland a substantially dropped amount of liquid crystal onto the substrateis input to the control unit, and a discharge amount of liquid crystal(dropped amount of liquid crystal onto the substrate) is controlledbased on the inputted information.

In FIG. 13, the control unit 200 includes: a dispensing amount settingunit 210 for setting a dispensing amount of liquid crystal to be droppedonto the liquid crystal panel; a dispensing amount compensating unit 220for compensating a dispensing amount of liquid crystal by controllingthe second motor 133 and controlling the fixation angle of the liquidcrystal discharge pump 140 when the preset dispensing amount of liquidcrystal by the dispensing amount setting unit 210 is different from asubstantial dispensing amount of liquid crystal onto the liquid crystalpanel; a motor driving unit 230 for discharging the preset dispensingamount of liquid crystal by the dispensing amount setting unit 210 bythe liquid crystal discharge pump 140 by controlling the first motor 131and the second motor 133; a substrate driving unit 240 for driving thesubstrate and thereby aligning a dropping position of liquid crystalwith the nozzle 150; and an outputting unit 250 for outputting each kindof information such as a substrate size, a panel size, a presetdispensing amount of liquid crystal, a current dispensing amount ofliquid crystal, a dispensing position, and etc. and ringing an alarm atthe time of an abnormality occurrence.

The outputting unit 250 is formed of a display such as a cathode raytube (CRT) or an LCD and a printer, thereby informing the user each kindof information regarding a dropping of liquid crystal and informing theuser a dropping abnormality by an alarm and etc. The dispensing amountsetting unit 210 is for setting a dispensing amount of liquid crystaldispensed onto the liquid crystal panel. An already calculated setamount can be manually input to the dispensing amount setting unit 210by the user. However, for more precise dispensing amount setting, anoptimum dispensing amount is automatically set on the basis of each kindof data.

As shown in FIG. 14, the dispensing amount setting unit 210 includes: aninputting unit 212 for inputting each kind of data such as a size of aliquid crystal panel to be fabricated, a number of sheets of liquidcrystal panels included in the substrate. A cell gap of the liquidcrystal panel (that is, a spacer height), and liquid crystalinformation; a total dispensing amount calculating unit 214 forcalculating a total dispensing amount of liquid crystal to be dispensedonto the liquid crystal panel and onto the substrate where a pluralityof liquid crystal panels are formed based on the data inputted to theinput unit 212; a single dispensing amount calculating unit 216 forcalculating a single dispensing amount of liquid crystal based on thecalculated total dispensing amount of liquid crystal; and a dispensingposition calculating unit 218 for calculating a dispensing position ofliquid crystal based on the calculated total dispensing amount of liquidcrystal.

The inputting unit 212 is for inputting data by a general controllingmeans such as a key board, a mouse, a touch panel, and etc. Data such asa size of a liquid crystal panel to be fabricated, a size of asubstrate, a cell gap of a liquid crystal panel, and etc. is input tothe inputting unit 212 by the user. The total dispensing amountcalculating unit 214 calculates a dispensing amount (Q) of liquidcrystal onto the liquid crystal panel based on an input panel size (d)and a cell gap (t) (Q=dxt), and calculates a total dispensing amount ofliquid crystal to be dispensed onto the substrate based on the number ofpanel sheets formed onto the substrate.

A single dispensing amount of liquid crystal and a dispensing positionof liquid crystal are determined based on a spread speed and a spreadregion of liquid crystal. The spread speed and the spread region ofliquid crystal are determined based on an area of a panel onto whichliquid crystal is dispensed, a liquid crystal characteristic such as aviscosity, and a substrate characteristic such as a pattern alignment.The single dispensing amount calculating unit 216 calculates a singledispensing amount of liquid crystal based on the calculated totaldispensing amount of liquid crystal, the panel area, the liquid crystalcharacteristic, and the substrate characteristic. Also, the dispensingposition calculating unit 218 calculates a spread region of a dispensedliquid crystal based on a dispensing amount of liquid crystal to bedispensed, a liquid crystal characteristic, and a substratecharacteristic, thereby calculating a dispensing position of liquidcrystal.

The calculated single dispensing amount and the dispensing position ofliquid crystal are respectively input to the motor driving unit 230 andthe substrate driving unit 240. A dispensing amount of liquid crystaldispensed onto the substrate is generally very minute as several mg. Toprecisely dispense the minute amount of liquid crystal is verydifficult, and the amount is easily varied according to each kind offactor.

In FIG. 15, the dispensing amount compensating unit 220 for compensatinga varied preset amount of liquid crystal includes: a dispensing amountmeasuring unit 222 for measuring a substantial dispensing amount ofliquid crystal dispensed onto the liquid crystal panel; a differentialvalue calculating unit 224 for calculating a differential value betweena dispensing amount of liquid crystal measured by the dispensing amountmeasuring unit 222 and a preset dispensing amount of liquid crystal setby the dispensing amount setting unit 210; a dispensing amountlimitation value setting unit 226 for setting minimum/maximum limitationvalues of the differential value of the dispensing amount calculated bythe differential value calculating unit 224 to prevent inferiority ofthe LCD device at the time of dispensing liquid crystal; and a comparingunit 228 for comparing the dispensing amount differential value inputtedfrom the differential value calculating unit 224 and the dispensingamount limitation value inputted from the dispensing amount limitationvalue setting unit 226, thereby outputting a signal to the motor drivingunit 230, and informing the user through the outputting unit 250.

The dispensing amount measuring unit 222 measures a dispensing amount ofliquid crystal by using a gravimeter (scale, not shown). The scalemeasures the dispensing amount of liquid crystal and is installed to beintegral or separate with/from the liquid crystal dispenser. That is,the dispensing amount of liquid crystal is measured by dispensing liquidcrystal onto a certain number of liquid crystal panels or a certainnumber of substrate sheets and then dispensing the liquid crystal onto ameasuring container provided at the scale with a certain number oftimes. The reason why the dispensing of a certain number of times isperformed onto the measuring container is because a single dispensingamount of liquid crystal is very minute as several mg. Since it isimpossible to precisely measure the minute amount, a dispensing ofliquid crystal of a certain number of times (for example, 50 times or100 times) is performed and a total weight is measured. Then, the totalweight is divided by the number of dispensing times to calculate asingle dispensing amount of liquid crystal.

Herein, a necessary value is a volume of a single dispensing amount nota weight of a single dispensing amount. The dispensing amount measuringunit 222 converts a weight of a calculated single dispensing amount intoa volume based on a stored data regarding the weight and volume ofliquid crystal being dispensed, and then outputs the value to thedifferential value calculating unit 224.

The dispensing amount limitation value setting unit 226 sets alimitation value for a differential value between a set value of liquidcrystal and a substantially measured value. Herein, the dispensingamount limitation value setting unit 226 can set one limitation value ora plurality of limitation values. When setting one limitation value, theset dispensing amount limitation value means an allowable value of adispensing amount of liquid crystal dispensed onto the liquid crystalpanel. That is, if liquid crystal is dispensed with an error within thelimitation value, inferiority of the LCD device is not generated. On thecontrary, when setting a plurality of limitation values, each settingvalue defines different values. For example, when of setting twolimitation values, a first limitation value defines an allowable valueof the liquid crystal dispensing and a second limitation value defines athreshold value that causes inferiority of the liquid crystaldispensing.

That is, if the differential value between the measured dispensingamount and the preset dispensing amount of liquid crystal obtained bythe comparing unit 228 is within the first limitation value, theinferiority of the LCD device is not generated by the liquid crystaldispensing and thereby the current liquid crystal dispensing iscontinuously performed. However, if the differential value exceeds thefirst limitation value and is within the second limitation value, thedifference between the differential value (the difference value betweenthe preset dispensing amount and the substantially measured dispensingamount, a dispensing amount compensating value) and the first limitationvalue is output to the motor driving unit 230 as a driving signal tocompensate the dispensing amount of liquid crystal to be within thefirst limitation value. Also, when the differential value exceeds thesecond limitation value, the dispensing of liquid crystal is stopped andan alarm is transmitted to the user through the outputting unit 250.

The first limitation value and the second limitation value aredetermined by a size of the liquid crystal panel and a dispensingpattern of liquid crystal. In the present invention, the firstlimitation value is set as approximately 0.3% of the preset dispensingamount, and the second limitation value is set as approximately 0.5% ofthe preset dispensing amount.

In FIG. 16, the motor driving unit 230 includes: a pulse value storingunit 234 for storing pulse value information regarding a dispensingamount of liquid crystal in order to drive the first motor 131 and thesecond motor 133; a pulse value converting unit 232 for converting asingle dispensing amount setting value input from the dispensing amountsetting unit 210 and a dispensing amount compensating value input fromthe dispensing amount compensating unit 220 into a pulse value; a firstmotor driving unit 236 for outputting a driving signal accordingly asthe single dispensing amount setting value is inputted and therebydriving the first motor 131 for operating the liquid crystal dischargepump 140; and a second motor driving unit 238 for outputting a drivingsignal for driving the second motor 133 accordingly as the pulse valueconverted by the pulse value converting unit 232 is inputted, andthereby varying a fixation angle of the liquid crystal discharge pump140.

Much rotation angle information of the second motor 133 regarding apulse value is stored in the pulse value storing unit 234. Therefore, asa pulse value is input, the second motor 133 is rotated as much as acorresponding angle and at the same time, the liquid crystal capacityamount controlling member 134 inserted into the rotational shaft 136 islinearly moved. Eventually, by the motion of the liquid crystal capacityamount controlling member 134, the fixation angle of the liquid crystaldischarge pump 140 to a fixing unit 149 is varied and thereby thedischarge amount of liquid crystal from the liquid crystal dischargepump 140 is varied. As aforementioned, the second motor 133 is a stepmotor and is rotated one time accordingly as approximately 1000 pulsesare input. That is, the second motor 133 is rotated with approximately0.36° for one pulse. Therefore, the rotation angle of the second motor133 can be precisely controlled by a pulse, and the discharge amount ofthe liquid crystal discharge pump 140 can be precisely controlled.

The liquid crystal dispensing method using the liquid crystal dispenserwill be explained in more detail with reference to the attacheddrawings. FIG. 17 is a flow chart of the liquid crystal dispensingmethod onto the substrate where a plurality of liquid crystal panels areformed using the liquid crystal dispenser. The method illustrated inFIG. 17 is for dispensing a preset amount of liquid crystal onto thesubstrate (or the liquid crystal panel) using the control unit 200.

First, the user inputs information such as a size of the liquid crystalpanel, a cell gap, and a liquid crystal characteristic to the inputtingunit 212 of the dispensing amount setting unit 210 by handling a keyboard, a mouse, and a touch panel (S301). According to this, the totaldispensing amount calculating unit 214 of the dispensing amount settingunit 210 calculates a total dispensing amount of liquid crystal to bedispensed onto the substrate (or the panel) (S302). Then, the singledispensing amount calculating unit 216 and the dispensing positioncalculating unit 218 calculate a single dispensing amount and adispensing position of liquid crystal to be dispensed onto the substratebased on the calculated total dispensing amount (S303, S305).

The substrate positioned at the lower position of the liquid crystaldispenser 120 moves in the x and y directions by a motor. The dispensingposition calculating unit 218 calculates a dispensing position of liquidcrystal based on the input total dispensing amount and the liquidcrystal characteristic information and the substrate information, andoperates the motor. According to this, the dispensing positioncalculating unit 218 moves the substrate so that the liquid crystaldispenser 120 can be positioned at the preset dispensing position(S304).

Under the state that the substrate is moved, the pulse value convertingunit 232 of the motor driving unit 230 calculates a pulse valuecorresponding to the calculated single dispensing amount of liquidcrystal (S306). Accordingly, as the calculated pulse value is input tothe second motor driving unit 238, the second motor 133 is driven toadjust the fixation angle of the liquid crystal discharge pump 140 forcorrespondence with the preset discharge amount (S307). After adjustingthe fixation angle of the liquid crystal discharge pump 140 as a presetangle (a preset dispensing amount or a preset discharge amount), thefirst motor driving unit 236 operates the first motor 131 to operate theliquid crystal discharge pump 140 and thereby starts to drop liquidcrystal onto the substrate (S308, S309).

In the liquid crystal dispenser of the present invention, the liquidcrystal discharge pump 140 is operated thus to dispense liquid crystalonto the substrate or the liquid crystal panel. Herein, the liquidcrystal discharge pump 140 is operated by the first motor 131, and aservo motor is used as the first motor 131. The dispensing amount ofliquid crystal dispensed onto the substrate, that is, the dischargeamount of liquid crystal discharged from the liquid crystal dischargepump 140, is varied according to the fixation angle of the liquidcrystal discharge pump 140 by the driving of the second motor 133 (i.e.,according to the up-down motion range of the piston 145 of the liquidcrystal discharge pump 140). Even if a servo motor can be used as thesecond motor 133, a step motor is preferably used. The reason is becausethe second motor 133 requires more precise motor driving than the firstmotor 131 and the step motor can be more precisely controlled than theservo motor. However, it is also possible to construct both the firstmotor 131 and the second motor 133 as the step motor.

A dispensing amount of liquid crystal dispensed onto the substrate isgenerally very minute (e.g. several mg). To precisely dispense theminute amount of liquid crystal is very difficult, and the amount iseasily varied according to each kind of factor. Accordingly, it isnecessary to dispense a precise amount of liquid crystal onto thesubstrate by compensating the dispensing amount of liquid crystaldispensed. The compensation of the dispensing amount of liquid crystalis performed by the dispensing amount compensating unit 220 of FIG. 13,which will be explained with reference to FIG. 18.

First, after dispensing liquid crystal with a preset number of times(for example, 50 times or 100 times, the dispensing of liquid crystalonto a preset number of sheets of the liquid crystal panel or thesubstrate), the dispensing amount of liquid crystal to be dispensed ismeasured by using a gravimeter (S401). Then, the measured dispensingamount is compared with a preset dispensing amount thus to determinewhether an error of the dispensing amount exists or not (S402, S403).When an error does not exist, it is judged as that the current amount ofliquid crystal being dispensed corresponds to the preset amount andthereby the dispensing is continuously performed. Also, when an errorexists, the dispensing amount compensating unit 220 calculates adifferential value between the preset dispensing amount and the measureddispensing amount (S404).

Then, the comparing unit 228 compares the calculated differential valueof the dispensing amount of liquid crystal with the second limitationvalue input from the dispensing amount limitation value setting unit226. Herein, the second limitation value is set as approximately 0.5% ofthe preset dispensing amount. If the differential value exceeds 0.5% ofthe preset dispensing amount of liquid crystal (S405), that is, themeasured dispensing amount of liquid crystal exceeds 0.5% of the presetdispensing amount or lacks, the comparing unit 228 judges as that thecurrent liquid crystal dispensing is abnormal. According to this, thecomparing unit 228 rings an alarm to the user and applies a signal tothe motor driving unit 230 thus to stop the driving of the first motor131, thereby stopping the dispensing of liquid crystal (S406, S407).

The reason why the dispensing of liquid crystal is stopped is asfollows. Since too great amount of liquid crystal or too small amount ofliquid crystal was dispensed onto the substrate (or the liquid crystalpanel), inferiority of the LCD device fabricated by the correspondingsubstrate (or the liquid crystal panel) may be generated. Therefore, thecurrent dispensing of liquid crystal is stopped, the correspondingsubstrate is discarded, and then the differential value of thedispensing amount of liquid crystal is controlled to be within the rangeof the second limitation value.

When the differential value of the dispensing amount of liquid crystalis less than the second limitation value, the differential value iscompared to the first limitation value (S408). Herein, the firstlimitation value is set as approximately 0.3% of the preset dispensingamount of liquid crystal. If the differential value of the dispensingamount of liquid crystal is less than the first limitation value, thatis, the measured dispensing amount does not exceed 0.3% of the presetdispensing amount of liquid crystal or does not lack, the comparing unit228 judges as that the current liquid crystal dispensing is normal, andthe current liquid crystal dispensing is continuously performed (S411).

If the differential value between the substantially dispensed dispensingamount (the measured dispensing amount) and the preset dispensing amountis greater than the first limitation value, the motor driving unit 240calculates a pulse value corresponding to the differential value (S409)and then outputs the calculated pulse value to the second motor 133 thusto drive the second motor 133 (S410). Accordingly, as the second motor133 is driven, the rotational shaft 136 of FIG. 7 is rotated and theliquid crystal capacity amount controlling member 134 screw-coupled tothe rotational shaft 136 is linearly moved. According to this, thefixation angle of the liquid crystal discharge pump 140 contacting theliquid crystal capacity amount controlling member 134 is varied, therebydispensing the compensated amount of liquid crystal onto the substrate(discharging from the liquid crystal discharge pump) (S411).

The fixation angle of the liquid crystal discharge pump 140 varied bythe liquid crystal capacity amount controlling member 134 is measured bythe linear variable differential transformer 139 to be input to themotor driving unit 240. Then, the motor driving unit 240 judges that theliquid crystal discharge pump 140 was controlled as a desired angle bythe fixation angle input from the linear variable differentialtransformer 139.

The compensating process of the dispensing amount of liquid crystal isrepeatedly performed. That is, whenever the liquid crystal dispensing ofa preset number of times is finished, the compensating process isrepeated thus to dispense a precise amount of liquid crystal onto thesubstrate.

As aforementioned, in the liquid crystal dispenser of the presentinvention, the fixation angle of the liquid crystal discharge pump 140fixed to the rotating member 157 of the liquid crystal dispenser iscontrolled to control the amount of liquid crystal drawn/dischargedinto/from the liquid crystal discharge pump 140, thereby preciselycontrolling the dispensing amount of liquid crystal.

A plurality of liquid crystal panels are formed on the substrate ontowhich liquid crystal is dispensed (for example, liquid crystal panels of6 sheets, 12 sheets, or 15 sheets can be formed on one substrate). Ifliquid crystal is dispensed onto the substrate where a plurality ofliquid crystal panels are formed using one liquid crystal dispenser, thedispensing time of liquid crystal onto one substrate is delayed, therebyreducing the fabrication efficiency of the LCD device.

Therefore, it is preferable to use the plurality of liquid crystaldispensers 120 for the fast dispensing of liquid crystal. The number ofthe liquid crystal dispensers 120 can be arbitrarily controlled by theprocessing conditions, and the number is not limited. FIG. 19 is a viewshowing the dispensing of liquid crystal onto the substrate 105 where 12liquid crystal panels 101 are formed using 4 liquid crystal dispensers(120 a-120 d), and FIG. 20 is a view showing the dispensing of liquidcrystal onto the substrate 105 where 15 liquid crystal panels 101 areformed using 4 liquid crystal dispensers (120 a-120 d). As shown, thenumber of liquid crystal dispensers 120 a-120 d can be same as thenumber of liquid crystal panels arranged in series or different fromthat.

Each liquid crystal dispensers 120 a-120 d can be separately controlled.That is, the dispensing amount setting unit 210 sets the dispensingamount of liquid crystal for each liquid crystal dispenser 120 a-120 d,and applies a pulse value corresponding to the set dispensing amount tothe second motor installed at each liquid crystal dispensers 120 a-120d. According to this, each liquid crystal dispenser 120 a-120 ddispenses liquid crystal onto the corresponding liquid crystal panel.When compensating the dispensing amount of liquid crystal, the currentdispensing amount of liquid crystal is measured for each liquid crystaldispenser 120 a-120 d and then is compared with the preset dispensingamount, thereby calculating the differential value and compensating thedispensing amount. As aforementioned, the plurality of liquid crystaldispensers 120 a-120 d are independently controlled to precisely controlthe dispensing amount of liquid crystal dispensed onto the plurality ofliquid crystal panels formed on the substrate.

In the present invention, the fixation angle of the liquid crystaldischarge pump is controlled by the step motor that can be preciselycontrolled, thereby controlling the dispensing amount of liquid crystaldispensed onto the substrate and thereby dispensing a precise amount ofliquid crystal onto the substrate at all times. Also, when compensatingthe dispensing amount of liquid crystal in the present invention, thepreset dispensing amount and the measured dispensing amount are comparedto the first and second limitation values. Herein, if the currentdispensing amount of liquid crystal is scarcely different from thepreset dispensing amount of liquid crystal, the liquid crystalcompensating is omitted. Also, if the current dispensing amount ofliquid crystal is excessively different from the preset dispensingamount of liquid crystal, the liquid crystal dispensing is stopped.According to this, faster control of the dispensing amount of liquidcrystal is possible.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the liquid crystaldispensing system and method of dispensing liquid crystal material usingthe same of the present invention without departing from the spirit orscope of the invention. Thus, it is intended that the present inventioncover the modifications and variations of this invention provided theycome within the scope of the appended claims and their equivalents.

1-30. (canceled)
 31. A liquid crystal dispensing system, comprising: aplurality of dispensers to dispense liquid crystal onto a substratedefining a plurality of unit panels; and a control unit configured tocontrol a dispensing amount of liquid crystal dispensed from the liquidcrystal dispenser and to compensate the dispensing amount when thedispensing amount of liquid crystal exceeds a limitation value bycomparing a differential value between a preset dispensing amount ofliquid crystal and a substantial measured dispensing amount onto thesubstrate with a first limitation value and a second limitation value.32. The system of claim 31, wherein the liquid crystal dispenserincludes: a container to contain liquid crystal; a discharge pump havinga case with a liquid crystal injection hole and a liquid crystaldischarge opening, a cylinder, a piston inserted into the cylinder andprovided with a groove at a lower portion thereof to draw in anddischarge liquid crystal by rotating and moving up and down, a suctionopening through which liquid crystal is drawn in as the piston moves,and a discharge opening through which liquid crystal discharged as thepiston moves; a first motor to drive the discharge pump; and a nozzledisposed at a lower portion of the discharge pump to dispense liquidcrystal discharged from the discharge pump.
 33. The system of claim 31,wherein the control unit includes: a control member contacting thedischarge pump to adjust a fixation angle of the discharge pump; asecond motor connected to the control member by a rotational shaft tocontrol the control member; and a dispensing amount setting unit to seta dispensing amount of liquid crystal and to output a signalcorresponding to the preset dispensing amount to the second motor. 34.The system of claim 31, wherein the control unit includes: a controllingmember contacting the discharge pump to adjust a fixation angle of thedischarge pump; a second motor connected to the controlling member bythe rotational shaft to control the controlling member; and a dispensingamount compensating unit to compensate a dispensing amount of liquidcrystal by comparing a measured dispensing amount with a predetermineddispensing amount.
 35. The system of claim 31, wherein the control unitincludes: a controlling member contacting the discharge pump to adjust afixation angle of the discharge pump; a second motor connected to thecontrolling member by the rotational shaft to control the controllingmember; a dispensing amount setting unit to set a dispensing amount ofliquid crystal and to output a signal corresponding to the presetdispensing amount to the second motor; and a dispensing amountcompensating unit to compensate a dispensing amount of liquid crystal bycomparing a measured dispensing amount with a dispensing amount set bythe dispensing amount setting unit.
 36. The system of claim 35, whereinthe dispensing amount compensating means includes: a dispensing amountmeasuring unit to measure a dispensing amount of liquid crystaldispensed onto a substrate; a differential value calculating unit tocalculate a differential value between a dispensing amount of liquidcrystal measured by the dispensing amount measuring unit and a presetdispensing amount of liquid crystal; a dispensing amount limitationvalue setting unit to set a limitation value of the differential valueof the dispensing amount; and a comparing unit to compare the dispensingamount differential value and the dispensing amount limitation valuerespectively input from the differential value calculating unit and thedispensing amount limitation value setting unit and to output a signalto the motor driving unit.
 37. The system of claim 36, wherein if thelimitation value exceeds the dispensing amount differential value, asignal is output to the second motor to compensate the dispensingamount.
 38. The system of claim 36, wherein if the limitation valueexceeds the differential value of the dispensing amount, a signal isoutput to the motor to stop dispensing the liquid crystal.
 39. Thesystem of claim 36, wherein the limitation value includes: a firstlimitation value at which a dispensing amount of liquid crystal iscompensated when the limitation value exceeds the differential value;and a second limitation value at which the liquid crystal dispensing isstopped when the limitation value exceeds the differential value. 40.The system of claim 39, wherein the first limitation value correspondsto 0.3% of a preset dispensing amount of liquid crystal.
 41. The systemof claim 39, wherein the second limitation value corresponds to 0.5% ofa preset dispensing amount of liquid crystal. 42-54. (canceled)